Do Larvae and Ovipositing Chironomus riparius (Diptera: Chironomidae) Females Avoid Copper-Contaminated Environments?

ABSTRACT

Studies on the avoidance behavior of aquatic organisms to contaminants have confirmed that such behavior can be relevant in field situations. However, almost all toxicity tests involve the forced exposure of organisms to toxicants. In particular, despite the importance of Chironomus riparius Meigen larvae in sediment toxicity testing, only a few studies on avoidance behavior have been performed. This study investigated the ability of different life stages of C. riparius, including ovipositing females, first-, second-, and fourth-instar larvae, to avoid copper-contaminated environments. Ovipositing females were given a choice between a control and copper solution (1.3 mg Cu l^{− 1}). First-instar larvae were provided with a choice between a control and a copper (2.0 mg Cu l^{− 1})-spiked sediment. Both second- and fourth-instars were exposed to a copper gradient (0.38–3.4 mg Cu l^{− 1}) in a flow-through system. None of the life stages avoided copper, even though the highest concentrations caused lethal effects on midges. The avoidance behavior of C. riparius is not a sensitive endpoint to assess copper sublethal toxicity.

Key words:

• avoidance
• test development
• water
• sediment
• toxicity

ACKNOWLEDGMENTS

This research was partially funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES-Brasil) through a doctoral grant to the first author (reference BEX0864-05-6), and by Fundação para a Ciência e a Tecnologia (FCT-Portugal) through a postdoctoral grant to the second author (reference SFRH/BPD/21721/2005) and the Pursuing Investigative Pathways in Environmental and Science Education Project (reference POCTI/CEC/34891/99).

Notes

*Identifies values significantly lower (p ≤ .05) than control.